HSP70 deficiency results in activation of c-Jun N-terminal kinase, extracellular signal-regulated kinase, and caspase-3 in hyperosmolarity-induced apoptosis
HSP70 deficiency results in activation of c-Jun N-terminal kinase, extracellular signal-regulated kinase, and caspase-3 in hyperosmolarity-induced apoptosis
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DOI：
10.1074/jbc.m412393200
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发表时间：
2005-02-25
影响因子：
4.8
通讯作者：
Seo, JS
中科院分区：
文献类型：
--
作者：
Lee, JS;Lee, JJ;Seo, JS
在这项研究中，我们利用hsp70.1-/-小鼠胚胎成纤维细胞（MEFs）检测了热休克蛋白70 （HSP70）在高渗诱导的凋亡通路中的功能。当细胞暴露于高渗应激时，缺乏HSP70会对细胞活力产生负面影响。在hsp70.1-/- mef中，Caspase-9和caspase-3被快速激活，在局灶黏附和细胞骨架分子中发生广泛的切割。相比之下，hsp70.1+/+ MEFs没有表现出caspase-9或caspase-3的激活，当细胞转移回等渗状态时，最终恢复完整的细胞形态。由于HSP70可能参与了丝裂原活化蛋白激酶（MAPK）的各种细胞活动的调控，我们也监测了MAPK的磷酸化。HSP70的缺失影响了c-Jun n末端激酶的磷酸化。然而，它对p38没有影响。在高渗诱导的hsp70.1-/- mef凋亡过程中，观察到细胞外信号调节激酶（ERK）持续磷酸化。PD98059对ERK活性的抑制加速了凋亡途径。ERK磷酸化与丝裂原活化的蛋白激酶磷酸酶-3从可溶性组分向不溶性组分的转移密切相关。我们的研究结果表明，HSP70对caspase-3激活的抑制作用足以抑制细胞凋亡，并且在高渗诱导的细胞凋亡中，HSP70对c-Jun n -末端激酶和ERK磷酸化具有调节作用。
In this study we examined the function of heat shock protein 70 (HSP70) in the hyperosmolarity-induced apoptotic pathway using hsp70.1-/- mouse embryonic fibroblasts (MEFs). When the cells were exposed to hyperosmotic stress, an absence of HSP70 negatively affected cell viability. Caspase-9 and caspase-3 were rapidly activated, and extensive cleavage occurred in focal adhesion and cytoskeletal molecules in the hsp70.1-/- MEFs. In contrast, hsp70.1+/+ MEFs exhibited no caspase-9 or caspase-3 activation and finally recovered intact cell morphology when cells were shifted back to an isosmotic state. Because HSP70 might be involved in the regulation of mitogen-activated protein kinase (MAPK) activities with regard to various cellular activities, we also monitored MAPK phosphorylation. The absence of HSP70 affected c-Jun N-terminal kinase phosphorylation. However, it had no effect on p38. Sustained phosphorylation of extracellular signal-regulated kinase (ERK) was observed during the hyperosmolarity-induced apoptosis of hsp70.1-/- MEFs. Inhibition of ERK activity by the treatment of PD98059 accelerated the apoptotic pathway. ERK phosphorylation was precisely correlated with shift of mitogen-activated protein kinase phosphatase-3 from the soluble to insoluble fraction. Our results demonstrate that the inhibitory effect of HSP70 on caspase-3 activation is sufficient to inhibit apoptosis and that HSP70 exhibits regulatory functions to c-Jun N-terminal kinase and ERK phosphorylation in hyperosmolarity-induced apoptosis.